Several methods of winding webbed material such as paper products upon cores have been used in the papermaking industry. Toilet tissue, paper towels, wipers, and the like are manufactured by first producing a webbed material, and then in a subsequent step winding (or rewinding) the webbed material upon cores for consumer use. One common method of transferring such material to cores is referred to as surface winding. A second common method is known as center winding.
There are many known types of rewinders which are based upon the principle of surface winding. The finished products are sometimes referred to as rolls or logs. In general, automatic surface rewinders comprise those rewinding systems in which logs are formed automatically in rapid succession. In surface rewinding, the log in the process of formation is rotated by surface contact of the roll with an external system of belts or rollers. Some known examples of surface winding apparatus and techniques are shown in U.S. Pat. Nos. 4,723,724; 6,050,519; 5,542,622; 5,853,140; 5,769,352; and 4,856,725.
In general, the process of surface rewinding produces a high number of rolls per unit time, and such finished rolls, when finished, are discharged to the exterior of the rewinder and collected in a sorter or intermediate storage receiver. Then, the free tail edge of the webbed material is glued onto the log to prevent unwinding of the end portion of the roll prior to cutting the log into smaller rolls for packaging.
Surface rewinding is a common method of rewinding paper products such as toilet tissue, paper towels, wipers, and other webbed materials upon finished logs for consumer use.
Another common method of rewinding rolls is by way of a process termed center winding. In general, center winding is accomplished using a web winding apparatus that includes a turret assembly, a core loading apparatus and a finished log stripping apparatus. Examples of such apparatus are shown in U.S. Pat. Nos. 5,690,297 and 5,810,282. In typical center winding processes, a turret assembly supports one or more rotating mandrels adapted for engaging hollow cores upon which a paper web is to be wound. Each mandrel is driven in a closed mandrel path, or processing loop, which may follow either a non-circular or circular pathway. In general, the turret assembly may be rotated continuously, and the web length per wound log is changed as the turret assembly is rotating. Usually, but not always, each step of the cycle occurs simultaneously. The turret cannot rotate to the next stage of processing until the steps at each active stage of the turret have been fully completed.
Typical center winding systems include several cycle positions including: (1) a loading position (for loading cores upon the mandrel), (2) a glue position (for applying glue to the core), (3) pre-spin position (for bringing a cored mandrel up to winding speed); (4) a transfer position (in which the web or paper is transferred to the spinning core at high speed); (5) a tail scaling position where adhesive is applied to the log or last sheet (for scaling the end); and (6) a log stripping position (in which the wound log is removed from the mandrel). In center winding operations, one respective step occurs at each position during the process, simultaneously.
In center winding apparatus, a disadvantage is that the rate determining step (i.e. the slowest step in the process) determines or fixes the speed at which the entire operation may progress. That is, even if a core may be loaded onto a mandrel in a very short period of time, or the gluing of paper upon the core may occur very quickly, the speed of the entire process can proceed no faster than the slowest step in the closed loop cycle. Thus, the slowest step (i.e., the step that takes the largest amount of elapsed time) will be the rate determining step which prevents the overall manufacturing process from producing a greater number of finished logs per unit time.
There are significant disadvantages to surface winding operations as well. One significant disadvantage of surface winding operations is that webbed products (such as toilet tissue or kitchen towels) which are very soft in texture and/or low in density cannot be reliably wound using high speed surface winding techniques. Rolls that contact the surface of the partially wound roll, i.e. the xe2x80x9crider rollsxe2x80x9d, must apply pressure to the exterior surface of the log in a precise manner, which leaves little room for tolerance or xe2x80x9cplayxe2x80x9d in the system. Low density logs do not possess the structural integrity necessary to resist surface winding forces without suffering plastic deformation and/or excessive log oscillation during rewind. Thus, surface rewinding is sometimes difficult in the case of soft, low density compressible webbed products, such as soft grades of toilet tissue and thick paper towels.
What is needed in the industry is a method and winding apparatus that facilitates faster rates of operation, for any type of webbed material, soft or otherwise. That is, a method that is capable of removing the influence of log cycle rate as a speed limitation, would be useful. A method which can employ mandrels in a more efficient manner, that facilitates the pre-loading of mandrels with cores in a process that is not directly time dependent upon the rewinding or the cores would be very desirable. That is, a system and apparatus that is capable of combining the advantages of center winding with the advantages of surface winding, while at the same time removing some of the limitations of each winding method, would be very desirable. An apparatus and method that is capable of rewinding rolls of any density and web length at a faster rate, in a more reliable manner, is desired.
An efficient system for winding webbed material upon a cored mandrel is provided. The system includes an elongated mandrel, the mandrel being adapted to receive a core upon its outer surface. Such cored mandrels of various quantities are provided in a holding or retention area, and then brought forth independently when needed in the process of winding webbed material into logs or rolls.
A first conveyor having a drive means for moving mandrels longitudinally along a drive train is provided. Rather than moving in a circular fashion or closed loop, the cored mandrels are collected and distributed to the process at the time they are needed. In most cases, the mandrels move in sequence, one after another, wherein at least the first end of said mandrel is adapted for engaging a drive means at appropriate times in the process.
A mandrel transfer station comprises a receiving mechanism for accepting cored mandrels, wherein the transfer station provides a means for winding webbed material upon said cored mandrel in a continuous process by applying a driving force to at least the first end of said cored mandrel to rotate the mandrel, thereby forming logs of webbed material. In some applications, the invention further comprises a gripping means applied to a first end of the mandrel to remove the mandrel from a drive train. In some applications of the invention, a log removal station is provided to remove logs of paper or tissue from said mandrels. A second conveyor may be adapted to move mandrels from a log removal station to a mandrel retention area.
In another application of the invention, a system is disclosed for winding webbed material upon cores in a continuous process. First, a plurality of elongated cylindrical mandrels are adapted to receive cores on their outer surface, the mandrels each having a first end and a second end. The cores have a circumferential surface on their outer periphery. A mandrel loading station is adapted for receiving a plurality of individual mandrels and loading the mandrels with cores to form cored mandrels. Then, a first conveyor with a drive assembly moves cored mandrels in a line along a drive train by engaging one or both ends of the cored mandrel with a drive. An adhesive application station is configured for placing adhesive at a specific predetermined circumferential location on the outer periphery of the core of the cored mandrels. A mandrel transfer station comprises a receiving means for accepting cored mandrels. The transfer station provides a means for winding webbed material upon the cored mandrels in a continuous process by applying a driving force to at least the first end of said cored mandrels. Cored logs of webbed material are formed, and ultimately may be cut into separate rolls of paper products.
In some applications of the invention, a belt and pulley system is used. The mandrel transfer station comprises a standard bedroll being configured to release said webbed material to a first cored mandrel once the first mandrel reaches the transfer position. The webbed material may be released by applying a driving force to at least the first end of the first cored mandrel, thereby pulling webbed material from the bedroll and forming a cored log of webbed material as the mandrel exits the transfer position and reaches a winding station. Also, at the same time, a second cored mandrel is pulled into the transfer position by a belt and pulley system.
In one aspect of the invention, an adhesive is placed longitudinally along the length of the cored mandrel at a specific circumferential location on the core, wherein the registration of the core with the drive means facilitates the subsequent placement of webbed material at a specific location upon the outer periphery of the core. This process enables adhesion of the webbed material to the core at a predetermined and specific location that uses a minimum amount of adhesive placed at precisely the location in which the glue is needed. The system is designed to reduce cost, increase production output, and avoid excess waste of adhesive.